Rotary bit for drilling wells



2 1927. Aug A. STEWART ROTARY BIT FOR DRILLING WELLS Filed March 15, 1926 2 Sheets-Sheet 1 Aug; 2, v A. STEWART ROTARY BIT FOR DRILLING WELLS Filed March 15, 1926 2 Sheets-Sheet 2 Patented Aug. 2, 1927.

UNITED STATES ALEXANDER STEWART, 01? DENVER, COLORADO.

ROTARY BIT FOB DRILLING WELLS.

Application filed larch 15 1826. Serial No. 94,888.

My invention relates to a new rotary-bit for drilling cased tubular wells.

And the objects of my invention are First: To provide an eccentrically mounted rotary well drilling bit, comprising a bit head having a plurality of rotary cutters that are mounted on its bottom end and are arranged to cut away a circular surface having a diameter somewhat greater than the diameter of the bit head.

Second: To provide an eccentrically mounted rotary drill bit that consists of a solid cylindrical bit head of a length to give it ample weight for the size of well being drilled; bit head being provided with a water passage through its axial center, and being connected to a hollow drill stem, by which water is conveyed to the passage in the bit, said bit head being provided on one side with means for cutting or reaming out the side wall of the well hole, and with means such as rotary cutters, which are adapted to cut away a circular surface of greater diameter than the bit head and which act to continuously crowd the drill against that side of the well directly opposite the side cutters, thus preventing the cutting of the well bottom in concentric grooves and also assuring that the diameter of the hole will be such as to prevent sticking of the drill when the same is withdrawn.

Third: To provide a well drilling bit for casing lined wells that rotates eccentrically to the axis of its supporting water conveying drill stem, thus preventing the drilling of a tight hole, said bit being provided with cutters which when broken or worn out can be quickly replaced by new ones; the body or bit head being formed with a conical upper end having radial members thereon which are adapted to cut away any pieces of earth or rock which may dro down upon the bit, the surface of the drill body being also provided with vertical grooves that extend to the bot-tom of the bit and allow any dirt and rock cuttings to fall through to the under side of the bit.

I attain these objects by the mechanism illustrated in the accompanying drawings, in which:.

Fig. l is a side view of the improved drill bit.

Fig. 2 is a top view of the same.

Fig. 3 is a bottom view thereof.

Fig. 4 is a vertical sectional view'through the bit, and

Fig. 5 is a view on a. reduced scale, showing a vertical sectional view of a well, and the improved drill therein as it appears when in operation.

Referring to the accompanying drawings:

The numeral 1 indicates the bit head which is in the form of a cylindrical steel block, the surface of which is formed with vertical grooves 2 which extend throughout the length of the head.

The upper portion of the head is preferably co n1cal,'as shown at 4, and the conical portion terminates in a ta red threaded shank 5, to which is secure a hollow drill stem 6 of the usual type, such drill stems comprising sections which are united by screw joint connections, as the well increases in depth.

The axial center of the threaded shank 5 is slightly eccentric to the center of the bit head as shown by the dotted circle X in Figures 2 and 3, which is struck from the center of the threaded shank and touches the bit head at its farthest point from the center of the said shank.

Upon the lower end of the bit head are mounted a series of cutters which are adapted to cut awa a circular surface of somewhat greater iameter than the diameter of the bit head and these cutters are arranged in the following manner :-The lower end of the bit head is formed with radial recesses 7 which coincide with the vertical grooves 2, and form pasage ways for water and for rock cuttings and earth removed by the cutters. A water passage 3 extends through the bit from top to bottom.

' A hole is formed diametericall through the bit head adjacent its lower en in which is passed a pin 9 upon which are rotatably mounted a series of circular cut-ting dlsks which are arranged in three groups; the outermost group comprising two cutters, the intermediate group comprising four cutters, and the third group comprising five cutters. The two cutters 10 of the first grou are in the form of circular bevel edge disks which are secured upon the pin 9 by a screw 11 which enters a threaded hole in the end of the pin, the head of the screw being large enough to overlap the. outerthe disks aga most disk, as shown in Fig. 34:, thus holding inst the bit head, which is cut away at this point as shown at 12 so as to permit the outer face of the outer disk to be nearly flush with the outer face of the bit head. The intermediategroup, is made up of circular bevel edged disks 13, similar to the disks 10, which lie in a recess 14, in .the bottom of the bit head which intersects grooves or recesses 15 extending through the bit head parallel with the pin 9, the recess 15, leaving a ridge or projection 95 through which the pin 9 passes. The third group of cutters is made up of circular cutting disks 16, of the same diameter as the disks 10 and 13, but their edges are formed with diagonally disposed cutting teeth as shown, for a purpose to be hereinafter explained, and these cutters lie in a recess 17 which also intersects the parallel recesses 15.

The pin 9 upon which the cutters 10, '13 and 16 are mounted, is formed near one end with an annular groove 8, and a locking pin 8 is passed through a. hole in the ridge 9 which intersects the annular groove 8 in the pinv 9 and thus locks the said pin against di lacement.

he cutting disks 13 and 16 are separated by a space, the disks 13, being on one side of the center of the head and the disk 16 bein on the other side of the center of the hea as shown in Fig. 3.

Short radial pins 18 and 19 are inserted in holes in the lower end portion of the bit head on opposite sides of the pin 9 and at angles of degrees to said pin, and are secured by locking pins in the same manner as the pin 9. Upon the pin 19 are mounted four circular bevel edged cutters 20 similar to the cutters 13 and 10, and these cutters lie in a recess 21 formed in the bottom of the head, and they travel in a circular path which lies between the paths of the cutters 13 and 10 as will be seen by reference to Fig. 3; 7

Upon the pin 18 is mounted a circula cutter 22, similar toone of the cutters 16, but of greater thickness; and the outer face of this cutter is flush with the outer face of the head; which is cut away for that purpose as shown at 23 in Fig. 1., This cutter travels in a path which extends outside the path of the cutters 10, and of the face of the bit head as shown by'the dotted line .Y in Fig. 3, thus insuring ample clearance for the bit head. I

A radial in 24 is insertedin a hole in the lower en of the bit head, at right angles to the pin 9, and beyond the pin 19, and this pin is also held in place by a locking pin, as in the case of the pins 9, 18 and 19, and a circular cutter 25 similar to the cutter 22, is mounted on the outer portion of this pin, the head being cut away, as shown at 26, to permit the outer face of the cutter to he 25% most clearly shown in Fig.1.

flush with the face of the head, the cutters 22 and 25 travelling in the same path as shown by the dotted line Y, Fig. 3.

B reference to Fig. 3, it will be seen that the arrangement of the cutters is such, that as the head rotates a circular area, of a diameter indicated by the line Y is cut away as the bit head descends, and the diameter of this area afi'ords ample clearance for the bit head. The beveled edges of the cutters 10, 13 and 20 act to continuously feed the bit head laterally, simultaneously with its rotary motion, such motion being permitted by that portion of the bit head which is eccentric to the axis of the drill stem. This motion of the bit head also prevents the cutters from forming and travelling in grooves, and the cutters are self sharpened as they cut down through the rock.

The cutters 16 have diagonally disposed teeth on their edges, aspreviously mentioned,

and this arrangement of the teeth does not interfere with the continuous lateral movement of the bit head. While I have shown the teeth inclined in onedirection on some of the cutters 16, and in the opposite direction on the others; it should be understood that the teeth on all of the out ters may be inclined in the same direction if desired. ,These cutters are rotated by engagement with the rock or earth as the case may be, and the teeth of the cutters 16, 2 1 and 25 are set to cut or gouge out the sur= face of rock or earth, as the cutters rotate, as will be understood by reference to Fig. 1.

The bit head is also provided with side cutters'27, 28 and 29 each of which has a bulged or curved surface which increases gradually'in diameter from each end toward the middle portion thereof, and the surfaces of these cutters are formed with diagonally bit head above these cutters being cut away as shown at 31, to provide flat horizontal surfaces 32, down through which vertical holes are drilled for the reception of the pins 30, these holes also extending into that portion of the bit head immediately below the cutters, thus providing bearing supports for both end portions of the pins. The cutter 27 is located above the cutter 22,- the cut ter 28 is located above the cutters 10 and the cutter '29 is located above the cut iielils e side cutters are designed more especially to give a smooth surface to the wall of the well hole so that'the casing sections can be more easily inserted in the well. seen that the water hole 3 in the bit head extends vertically through the same to about its middle portion and then inclines to one It will be rounding the axial center of the well.

bit head are formed three. or more radial cutters 33, in the form of knife edged ribs or bars, and these bars are adapted to cut or wear-away any large pieces of dislodged rock or earth WlllOh may drop down on the bit head.

The vertical grooves or channels 2 in the bit head .act in connection with the radial recesses in the bottom end of the head to ermit water coming down through the iiead to pass out from under the head and upward around the head as will be understood by reference to Figure 3 of the drawhe cutters 22 and 25 are held upon their respective pins 18and 24, by the heads of screws 2 and 5 respectively which are screwed into threaded holes in the ends of the pins. In operation, one end of a drill stem 6 is screwed to the threaded shank 5 of the bit head and the stem is supported and rotated in the usual manner, the direction of rotation being indicated by the arrows in Figures 1 and 2. As the head rotates the cutters 22 and 25 cut a path representing the greatest diameter of the well hole, the cutters 22 being in advance and followed by the cutter 10 which travel in the same path and in advance of the cutter 25. The cutters 20 and 13 which travel in different paths, cut away all the surface between the cutters 22-25 and a point adjacent the center of the well hole the cutters 16, acting in conjunction with the cutter 13 in removing the surface immediately SIX- s the cutters 10, 16 and 20 are on that side of the head which is concentric with the drill stem, and as they act to continuously move the head laterally, the head is thereby given a revolving movement in connection with its rotary movement, by which the whole circular surface of the well bottom including that part at the immediate center, is cut away, and circular grooves which would otherwise be formed by the cutters 10, 13 and 20 are prevented.

As the bit decends into the ground or rock, the side cutters 27, 28 and 29 give a smooth finish to the surface of the hole and at the same time water is forced down through the drill stem to and through the hole 3, in the bit head and asses out under the bit head andupthroug the channel 2 therein and into the well hole, thus washing out the cuttings from under and around the bit head, which are carried up through the well hole with the water which discharges in a continued stream at the top of the well hole. By the arrangement of the cutters and the combined rotary and revolving movement of the bit, a hole is made which is enough larger in diameter than that of the bit head to prevent binding of the same when in operation, and to enable the head to be withdrawn from the hole without sticking.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is

1. The combination in a tubular well drilling bit; of a rotatable stem comprising a water supply pipe, a drill bit consisting of a body portion detachably secured eccentrically to the lower end of the water supplying pipe; said body portion being provided with recesses in its periphery on one side thereof; rotary cutters mounted therein on vertical shafts secured in said body portion; said body portions having its upper end sloping downwardly from its connection with its supporting stem, and radial ridges on said downwardly sloping surface having a cutting edge; said body portion being also provided with radial shafts on its bottom surface provided with a plurality of rotary cutters, arranged to cut out the entire circular area of the bottom of the well hole being drilled by said rotary bit.

2. The combination with a rotary bit for drilling cased wells, of a hollow water supplying pipe, a short solid one piece body portion, said body portion being mounted eccentrically on the lower end of said water supplying pipe whereby one side of it ex tends at a greater radial distance from the axial center of said ipe than the other side; the side of said b0 y portion farthest from the axial center of the pipe being provided with four different arrangements of rotary cutters mounted on shafts journaled in the bottom of said rotary bit; said shafts being radially disposed, a group of separate rotary cutters mounted on a shaft, journaled in the bottom portion of the rotary bit, and extending across the same; a group of cutters on the outer long end of said shaft and a group of cutters between said end group of cutters and the center of said shaft; means for securing said cutters on said shafts and means for securing said shafts to the bottom of said body portion of said rotary bit.

3. Awell drilling bit comprising a cylindrical bit head having vertical channels in its surface and a threaded shank on its u per ,end which is eccentric to the longitud nal center of the head, a vertically disposed, passage being formed through said shanks and extending out through the lower end of the head, rotary cutters mounted in thelower end of the head in radial lines, rotary cutters mounted in that portion of the wall of said head farthest from the. axis of said shank, said cutters being arranged to cut a greater diameter than that of the head, said threaded shank being adapted to receive a hollow drill stem.

4L A rotary well drilling bit of the character described, comprising a cylindrical bit said cutters having beveled edges which pitch toward the opposite side of the head and which-are adapted to continuously move the head to one side simultaneously with its rotary movement, rotary side cutters in that part of the wall of the head which is farthest from the threaded stem. said head having a vertically disposed water wpassage extending therethrough.

5. A rotary well drilling bit comprising a head having a threaded drill-stem-receiving shank which is eccentric to the longitudinal center of the head, rotary toothed cutters on the lower end of said head and rotary bevel edged disk cutters inside the path of travel of the toothed cutters, the bevelof the edges of said disk cutters being toward the axis of the head thereby acting to continuously move the head in the direction of its side which is nearest the axis of the threaded shank.

6. A rotary well drilling bit comprising a bit head, having a hollow drill stem which is eccentric to the center of the head, rotary diagonally toothed cutters on the lower end of said head, which travel in a path of greater diameter than the head, and rotary disk cutters having radially disposed axes, which travel in paths of less diameter than the first mentioned cutters, the bevel of the edges of said cutters being toward the axis of the head, thereby acting to continuously move the head in thedirection of its side which is nearest the axis of the drill stem, and rotary spirally toothed cutters in that side of the head which is farthest from the drill stem, said head having a vertically disthree last mentioned groups having beveled edges which pitch toward the center of the head, radial pins in said head and rotary cutters thereon which travel in a path of greater diameter than the head, one of said cutters being in advance of the bevel edged cutters and the other following them, said bevel edged cutters acting to continuously move said head in the direction of its side which is nearest theaxis of the drill stem,

head which is farthest from the axis of the drill stem.

8. The combination with a cylindrical drill head having a drill stem eccentric t0 the longitudinal center of the head; of a diametrical shaft in the bottom end of said head; spaced groups of disk cutters on said shaft, said cutters being in that part of the head whose periphery 'is farthest from the axis of the drill stem, a group of diagonally toothed rotary cutters on the opposite portion of said shaft, the innermost cutter being adjacent the axial line of the drill stem, a radial pin in the bottom end of the head, disk cutters mounted-on said pin to travel in a path between the paths of the aforesaid groups of disk cutters, other radial pins in the bottom end of said head and diagonally toothed cutters on said pins adapted Ito travel in a path of greater diameter than the diameter of the head. and rotary cutters in that part of the wall'of the head farthest from the axial center of the drill stem.

In testimony whereof I aflix my signature,

ALEXANDER STEWART.

and rotary side cutters in thatside of the 

